Science Musings Blog

Monday, September 17, 2012

Remembering the Voyagers

In Shakespeare's The Tempest, Miranda grows to the age of sixteen on an ocean isle with no human companions other than her father Prospero and the monster Caliban. When storm and shipwreck bring others to the island she is suddenly awakened to the variety and beauty of mankind. "O brave new world," she exclaims, dazzled, "that has such people in't!"

We have been hearing lately about the almost forgotten spacecrafts Voyager 1 and Voyager 2, launched 35 years ago to explore the outer solar system. They have long since completed their planetary mission -- although still in occasional contact with Earth -- and are now drifting ever deeper into space. The current question concerns whether they can be said to have exited the Solar System.

In 1986, after a voyage of 8 ½ years, Voyager 2 sailed past Miranda, one of the moons of Uranus, a little world about the size of Colorado. The image beamed back to Earth was of stunning clarity. It showed features no larger than the Boston Common. Miranda's icy surface was pocked with craters and lidded with mysterious looping folds o f crinkled crust. From the deeps of space and the abysm of time Miranda seemed to wink. And we, seeing the image, could only blink with wonder at a universe that has such objects in it.

The Voyagers outperformed the most optimistic expectations of the engineers and scientists who launched them in 1977. The images beamed back to Earth were breathtaking, wonders of the space age. First came an encounter with giant Jupiter, the monster planet, eddied with storms of yellow, red, and orange like a can of freshly pigmented paint stirred with a stick. And against that improbable backdrop of psychedelic drapery, the moons. Sulphurus Io, plumed with volcanic activity, bubbling with a nether-worldly fire. Reticulated Europa, crevassed like arctic sea ice, cobwebbed with thin ridges and strangely devoid of craters. Ganymede, the frosted giant, its surface trenched and blasted like the battlefield at Verdun. And, Callisto, ice crusted, densely cratered; a huge many-circled impact feature on Callisto gives that moon the appearance of a struck brass gong.

We gaped. We marveled.

Then on to ringed Saturn, which the Voyagers reached in 1980 and 1981. No saint painted by Giotto ever wore a more splendid halo than huge Saturn.

Each of Saturn's moons held its own surprise. Mimas, with its perfect dimpled moon-sized crater; Mimas looks so much like Darth Vader's Death Star spaceship that one would be willing to credit George Lucas with a kind of spooky prescience. Bright-dark Iapetus, its leading hemisphere only one-tenth as bright as the icy trailing backside. Enigmatic Enceladus, almost a twin to bigger Ganymede. Tumbling, chunky Hyperion. Tethys, Rhea, and Dione, like wheels of green (and pink, and yellow) cheese. And Titan, the only one of all these worlds large enough to be shrouded in gas.

Breathtaking.

And on went Voyager 2, to Uranus and Neptune, and yet more wonders. But enough! Enough gush. Those were thrilling days. We have become almost blasé about planetary exploration. The Voyagers, those plucky little marvels, were revelations.